XO-3b

Planetbox begin
name = XO-3bcite journal |url=http://fr.arxiv.org/abs/0712.4283 |title=XO-3b: A Massive Planet in an Eccentric Orbit Transiting an F5V Star |journal=The Astrophysical Journal |eprint=0712.4283 |class=astro-ph |year=2007 |accessdate=2008-01-02] Planetbox star
star = XO-3
constell = Camelopardalis
RA = RA|04|21|53
DEC = DEC|+57|49|01
dist_ly = 850 ± 75
dist_pc = 260 ± 23
class = F5VPlanetbox orbit
semimajor = 0.0454 ± 0.00082
period = 3.1915239 ± 0.00023
eccentricity = 0.26 ± 0.017
inclination = 84.2 ± 0.54
ang_dist = 0.175
long_peri = 345.8 ± 7.3
t_peri = 2454024.84 ± 0.02;
2454449.86816 ± 0.00023
(transit time)
semi-amp = 420Planetbox character
mass = 11.79 ± 0.59
radius = 1.217 ± 0.073
density = 8.67fact|date=January 2008
gravity = 21.02fact|date=January 2008Planetbox discovery
discovery_date = May 30, 2007
discoverers = Krull et al.
discovery_method = transit & radial velocity
discovery_site = Honolulu, Hawaii
discovery_status=Published

XO-3b is an exoplanet with less than twelve times the mass of Jupiter, and an orbit around its parent star of more than three days. [http://www.space.com/scienceastronomy/070530_odd_planet.html Oddball Planet Puzzles Astronomers, "Space.com"] ] The radius of this object is 1.217 times that of Jupiter. Its large size of the planet is believed to be caused by the intense heating of its parent star at very small orbit and because of the huge mass the object probably raidiates enough of its internal heat making it glow red hot. Astronomers announced their discovery on May 30th, 2007 at the American Astronomical Society in Honolulu, Hawaii. Its discovery is attributed to the combined effort of amateur and professional astronomers working together on the XO Project using a telescope located on the Haleakala summit in Hawaii. [http://timesofindia.indiatimes.com/HealthScience/Space_oddity_Astronomers_discover_giant_planet/articleshow/2088130.cms Space oddity: Astronomers discover giant planet, "The Times of India"] ]

Dubbed an "oddball" planet, the planet stands out from over 200 other extrasolar planets as the most massive planet found in close proximity to a star, yet the orbit is significantly elliptical instead of circular, as would be expected. It is also considered a transiting planet, passing in front of its parent star during each orbit. It is the third such planet to be found by the XO Project which was specifically created to locate them. [ [http://www.eurekalert.org/pub_releases/2007-05/ru-xsp052507.php XO-3 b: Supersized planet or oasis in the 'brown dwarf desert'?, "EurekAlert!"] ]

Orbital inclination

As of August 2008, the most recent calculation of XO-3b's Rossiter-McLaughlin effect and so spin-orbit angle was that of Hebrard. It is very misaligned compared with other transiting planets, [cite arXiv | title= Measuring accurate transit parameters | author=Joshua N. Winn | eprint=0807.4929v2 |class=astro-ph |year=2008] at +70 ± 15 degrees. [cite arXiv | doi=10.1051/0004-6361:200810056 |title=Misaligned spin-orbit in the XO-3 planetary system? | author=G. Hebrard "et al." | eprint=0806.0719 |class=astro-ph |year=2008] This may indicate that in the past an encounter with another planet altered its orbit, kicking it out of the plane of the planetary system. [cite news|url=http://space.newscientist.com/article/mg19926744.400-planets-strange-orbit-points-to-planetary-billiards.html|title=Planet's strange orbit points to planetary billiards|author=Powell, Devin|date=2008-09-22|work=New Scientist|accessdate=2008-09-23] Another planetary system that may have also undergone such planet-planet interactions is Upsilon Andromedae. [cite journal|url=http://simbad.u-strasbg.fr/cgi-bin/cdsbib?2005Natur.434..873F|author=Ford, E. "et al."|title=Planet-planet scattering in the upsilon Andromedae system|journal=Nature|volume=434|pages=873–876|year=2005|doi=10.1038/nature03427]

Controversy

There is currently a debate over the classification of this object as either a planet or a brown dwarf. One of the leading astronomers in this discussion is Christopher Johns-Krull, who indicated that the debate is still quite lively. This is not particularly unusual or strange, as it wouldn't be the first of many brown dwarfs orbiting mother stars.

The light curve that better match the steepness of ingress and egress implies a planetary radius of 1.32 ± 0.15 R_J and a mass of 11.71 ± 0.46 M_J.

References

External links

* [http://exoplanet.eu/planet.php?p1=XO-3&p2=b The Extrasolar Planets Encyclopaedia: Notes for XO-3 b]